1. Field of the Invention
This invention relates to an improved device connected in the exhaust pipe of an automobile for the catalytic purification of exhaust gas.
2. Description of the Prior Art
There are known a variety of devices used for the catalytic purification of exhaust gas from an automobile. They have, however, the drawback of failing to purify exhaust gas satisfactorily, since the catalyst which is usually employed can work only at a temperature of at least about 400.degree. C. The catalyst is so cold during the beginning of engine operation, particularly during the cold season of the year, as to require a considerably long time before it reaches its working temperature. As a natural consequence, the device allows a large amount of toxic gas to leave the automobile. It is estimated that about 70% of the exhaust gas which is produced during the engine operation is allowed to leave the automobile without being purified.
There is also known a precatalyzer installed close to the engine to enable the catalyst to reach its working temperature more rapidly. Even this device is, however, unsatisfactory for the effective purification of exhaust gas.